1. Field of the Invention
The invention relates to a vibration generator comprising two, three, or four groups of shafts, on which at least two groups of imbalances are disposed. The shafts are connected with at least one drive, which rotates the shafts at different speeds of rotation.
2. The Prior Art
In construction, vibration generators are used to introduce objects, such as profiles, into the ground, or to draw them from the ground, or also to compact ground material. The ground is excited by vibration, and thereby achieves a “pseudo-fluid” state. The goods to be driven in can then be pressed into the construction ground by a static top load. The vibration is characterized by a linear movement and is generated by rotating imbalances that run in opposite directions, in pairs.
Vibration generators are vibration exciters having a linear effect, whose centrifugal force is generated by rotating imbalances. These vibration exciters move at a changeable speed. The size of the imbalance is also referred to as static moment. The progression of the speed of the linear vibration exciter corresponds to a periodically recurring function, particularly a sine function. On the basis of the sine-shaped progression of the force effect generated by the rotating imbalance masses, a drive that acts alternately in the forward drive direction and counter to it, with time offset, is produced. This effect is determined, in the final analysis, by static forces, particularly the inherent weight and static top loads. Without the superimposition of static forces on the vibration, the material being driven would not move forward, but rather simply vibrate back and forth. It is a disadvantage of the previously known systems that the pile-driving process, with the aforementioned sine-shaped force progression, demonstrates significant energy consumption, which is additionally increased due to friction of the material being driven, in the ground. The energy expended for the vibration generator brings about almost no forward drive.